Head fixation device

ABSTRACT

Head fixation devices and methods of fixating heads of patients for surgical procedures. The head fixation devices generally respectively comprise a skull clamp, a skull clamp arc assembly movable relative to the skull clamp, and a plurality of skull pins operable to engage and fixate heads of patients during neurosurgical and cervical spine procedures. The skull clamp can comprise a single skull pin on each end of the clamp. The two skull pins apply substantially equal compressive forces to the head of a patient. The skull clamp arc assembly, and an arc skull pin thereof, is pivotable to engage and disengage the patient&#39;s head for additional fixation support of the head.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 12/478,103,filed on Jun. 4, 2009 (pending), which claims the benefit of U.S.Provisional Application Ser. No. 61/058,939, filed Jun. 5, 2008, thedisclosures of which are incorporated by reference.

BACKGROUND

Embodiments of the present disclosure relate generally to head fixationdevices for use with surgical head frames during surgical procedures.More particularly, the embodiments relate to head fixation devicesrespectively comprising a skull clamp, a skull clamp arc assemblymovable relative to the skull clamp, and a plurality of skull pins toengage and fixate heads of patients during surgical procedures.

Conventional three pin, C-shaped skull clamps typically are used withsurgical head fixation devices to support a head of a patient duringneurosurgical and cervical spine procedures. The skull clamp works likea C-clamp, or vise, to keep the head of the patient steady as surgeriesare performed. Typically, on one side of the skull clamp is a rocker armcontaining two skull pins and on the opposing side is a mechanism toengage and advance a third pin into the skull of the patient. Betweenabout sixty pounds and about eighty pounds of compressive forcetypically are applied to the head with the third skull pin. It is thencustomary to assume that, as the third skull pin is driven into theskull, each of the rocker arm skull pins will apply approximately halfof the force being applied by the third pin, or between about thirtypounds and about forty pounds of compressive force, to the head of anadult patient if the skull clamp is properly positioned and applied onthe patient's head.

However, problems may arise if the rocker arm skull pins are notproperly positioned or applied to the head. For example, if the rockerarm is not aligned properly with the third pin, the compressive forceapplied by each of the two rocker arm skull pins may not be equal. Thisinequity in applied compressive forces could negatively affect theability of the conventional skull clamp to fixate the head of thepatient. Additionally, if the rocker arm is misaligned with the thirdskull pin, the rocker arm skull pins may not apply an appropriatecompressive force, thereby potentially resulting in rotation of thepatient's head during a surgical procedure and/or in slippage of theskull pins along the head, which may cause injurious skin and tissuetears on the head.

As such, based on the foregoing, there exists a need for a head fixationdevice comprising a skull clamp and at least two opposing skull pinspositioned such that they apply substantially equal compressive forcesto each side of the head and at least one movable arc skull pin offsetfrom the opposing skull pins to engage and further fixate a patient'shead during a surgical procedure.

SUMMARY

It is against the above background that embodiments of the presentdisclosure generally relate to head fixation devices that respectivelycomprise a skull clamp, a skull clamp arc assembly movable relative tothe skull clamp, and a plurality of skull pins to engage and fixateheads of patients during neurosurgical and cervical spine procedures.The skull clamp comprises at least one skull pin on each end of theclamp. The two skull pins apply substantially equal compressive forcesto the head of a patient. The skull clamp arc assembly, and an arc skullpin thereof, is pivotable to engage and disengage the patient's head foradditional fixation support of the head.

In accordance with one embodiment, a head fixation device comprises askull clamp, a first skull pin, a second skull pin, and a skull clamparc assembly. The skull clamp is positionable about a head of a patientand comprises a first end and a second end opposing the first end. Thefirst skull pin is provided to the first end of the skull clamp and thesecond skull pin is provided to the second end of the skull clamp,wherein the first and second skull pins are aligned in opposition alongan axis. At least one of the first and second skull pins is movablerelative to the first and second ends such that the first and secondskull pins engage and disengage the head of the patient when the skullclamp is positioned thereabout. The skull clamp arc assembly comprisesan arc skull pin and extends from one of the first and second ends ofthe skull clamp such that the arc skull pin is offset from the axis. Theskull clamp arc assembly is movable relative to the first and secondends of the skull clamp such that the arc skull pin is operable toengage and disengage the head of the patient with movement of the skullclamp arc assembly.

In accordance with another embodiment, the skull clamp arc assembly ofthe head fixation device is rotatable relative to the one of the firstand second ends from which the skull clamp arc assembly extends suchthat the skull clamp arc assembly rotates about the horizontal axisdefining the axis. In addition, the skull clamp arc assembly ispivotable relative to the one of the first and second ends such that thearc skull pin pivots toward and away from the horizontal axis definingthe axis.

In accordance with yet another embodiment, a method of fixating a headof a patient comprises providing a head fixation device operable tofixate the head of the patient. The head fixation device comprises: askull clamp comprising a first end and a second end opposing the firstend, a first skull pin provided to the first end of the skull clamp anda second skull pin provided to the second end of the skull clamp,wherein the first and second skull pins are aligned in opposition alongan axis, and a skull clamp arc assembly comprising an arc skull pin. Theskull clamp arc assembly extends from one of the first and second endsof the skull clamp such that the arc skull pin is offset from the axis.The method further comprises positioning the head fixation device aboutthe head of the patient such that the first and second ends of the skullclamp are positioned about the head of the patient. Thereafter, themethod comprises moving at least one of the first and second skull pinsrelative to the first and second ends of the skull clamp such that thefirst and second skull pins engage the first and second sides of thehead of the patient and rotating the skull clamp arc assembly relativeto the first and second ends such that the skull clamp arc assemblyrotates about the axis to selectively position the arc skull pin over athird side of the head of the patient. In addition, the method comprisespivoting the skull clamp arc assembly relative to the first and secondends such that the arc skull pin pivots to engage the third side of thehead of the patient. The engagements of the first, second, and thirdsides of the head of the patient by the first skull pin, the secondskull pin, and the arc skull pin, respectively, sufficiently fixate thehead of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of specific embodiments can be bestunderstood when read in conjunction with the following drawings, wherelike structure is indicated with like reference numerals and in which:

FIG. 1A illustrates a frontal view of a head fixation device accordingto one embodiment of the present disclosure;

FIG. 1B illustrates a magnified view of a skull clamp arc assembly of ahead fixation device according to the embodiment of the presentdisclosure illustrated in FIG. 1A where the skull clamp arc assembly ispivoted to a maximum pivot away from the axis along which first andsecond skull pins are aligned;

FIG. 1C illustrates a magnified view of a skull clamp arc assembly ofthe head fixation device illustrated in FIG. 1A where the skull clamparc assembly is pivoted toward the axis along which first and secondskull pins are aligned;

FIG. 2 illustrates a frontal view of a head fixation device according toanother embodiment of the present disclosure;

FIG. 3 illustrates a view of a skull clamp arc assembly and a lockingassembly of a head fixation device according to another embodiment ofthe present disclosure;

FIG. 4 illustrates a cross-sectional view of a skull pin according toanother embodiment of the present disclosure;

FIG. 5 illustrates a cross-sectional view of a rocker guide assembly ofa head fixation device according to another embodiment of the presentdisclosure;

FIG. 6A illustrates a cross-sectional view of a lower rocker assembly ofa head fixation device according to another embodiment of the presentdisclosure;

FIGS. 6B and 6C illustrate a frontal view and a side view, respectively,of a lower rocker assembly comprising a ratcheted configuration of ahead fixation device according to another embodiment of the presentdisclosure;

FIGS. 7A and 7B illustrate a frontal view and a side view, respectively,of an upper rocker assembly comprising a ratcheted configuration of ahead fixation device according to another embodiment of the presentdisclosure;

FIG. 8 illustrates a frontal view of a head fixation device according toanother embodiment of the present disclosure;

FIG. 9 illustrates an exploded view of a skull pin assembly of the headfixation device illustrated in FIG. 8;

FIG. 10A illustrates a frontal view of a skull clamp arc assembly of ahead fixation device according to another embodiment of the presentdisclosure; and

FIG. 10B illustrates an exploded view of the skull clamp arc assembly ofthe head fixation device illustrated in FIG. 10A.

The embodiments set forth in the drawings are illustrative in nature andare not intended to be limiting of the embodiments defined by theclaims. Moreover, individual aspects of the drawings and the embodimentswill be more fully apparent and understood in view of the detaileddescription that follows.

DETAILED DESCRIPTION

Referring initially to FIG. 1A, a head fixation device 20 comprises askull clamp 22, a first skull pin 24A and a second skull pin 24B, and askull clamp assembly 26 that extends from the skull clamp 22. The skullclamp 22 is positionable about a head of a patient. The skull clamp 22generally, but not necessarily, comprises a C-clamp-like shape includinga body 28, a first end 30A, and a second end 30B opposing the first end30A. It also is contemplated that the skull clamp 22 may comprise acircular, oval, polygonal, or other shape that may be configured tofunction as disclosed herein or otherwise inferable there-from.

The first and second ends 30A, 30B of the C-clamp-like shape skull clamp22 are separated by a gap 32 sufficient to accommodate the head of achild or adult patient. The body 28 of the skull clamp 22 may comprisetwo complementary ratcheting arms 34A, 34B. The ratcheting arms 34A, 34Bmay be operable to move relative to one another via a shared ratchetingmechanism 36 to adjust the length of the gap 32 separating the first andsecond ends 30A, 30B of the skull clamp 22. The ratcheting mechanism 36may comprise a spring-biased pin 37 to control a locking and unlockingof the ratcheting arms 34A, 34B to preclude and permit, respectively,lateral movement thereof. The ratcheting arms 34A, 34B may comprise gripareas 38A, 38B designed to facilitate a user's gripping of theratcheting arms 34A, 34B to adjust the length of the gap 32. It also iscontemplated that one or more mechanisms in addition to or in thealternative of the ratcheting mechanism 36 may be used to permit andcontrol adjustment of the length of the gap 32 separating the first andsecond ends 30A, 30B.

The first and second skull pins 24A, 24B are provided to the first andsecond ends 30A, 30B, respectively, and, as such, are separated by thegap 32. Thereby, the first and second skull pins 24A, 24B move closertogether and farther apart in accordance with the movement of the skullclamp body 28, whether via the ratcheting mechanism 36 or otherwise. Inaddition, the first and second skull pins 24A, 24B are aligned inopposition along an axis 40. As used herein, “aligned in oppositionalong an/the axis” refers generally to at least a respective portion ofthe first and second skull pins 24A, 24B being substantially alignedalong a line and is not intended to imply that the pins 24A, 24B, whenengaged with the head of a patient, are necessarily applied to directlyopposite points on the head. As such, it is contemplated that not onlymay the first and second pins 24A, 24B be parallel, or substantiallyparallel, but also that portions of the skull pins 24A, 24B may beoffset from one another at an angle, whether acutely or obtusely, orotherwise, wherein at least a respective portion of the offset skullpins, such as respective skull-engaging tips thereof, remainsubstantially aligned along the line.

Further, at least one of the first and second skull pins 24A, 24B may bemovable relative to, and independent of, the first and second ends 30A,30B of the skull clamp 22 so as to engage and disengage the head of thepatient when the skull clamp 22 is positioned thereabout. Moreparticularly, the skull pins 24A, 24B individually may comprise a tip 42secured to the first and second ends 30A, 30B, as shown in FIG. 1A withrespect to the second skull pin 24B, and operable to engage the head ofa patient. Alternatively, as shown in FIG. 1A with respect to the firstskull pin 24A and in greater detail in FIGS. 4 and 9, the skull pins24A/24A″, 24B/24B″ individually may comprise, in addition to the tip 42,a plunger 44/44″, a plunger guide 46/46″, and a compression spring48/48″ that may cooperate to permit lateral movement of the skull pins24A/24A″, 24B/24B″ along the axis 40 relative to, and independent of,the first and second ends 30A, 30B of the skull clamp 22. The plunger 44may be operable to support the tip 42, while the plunger guide 46 may beoperable to control movement of the plunger 44 and the tip 42. Thecompression spring 48 may be operable to translate movement of theplunger guide 46 to the plunger 44 and the tip 42, whether that movementbe toward the opposing skull pin or away there-from. The tip 42, whethersecured to the first or second end 30A, 30B or supported by the plunger44, may be removed from the head fixation device 20 and discarded as adisposable component of the device 20 and, thereafter, replaced withanother tip 42.

As shown in FIGS. 4 and 9, the plunger guide 46/46″ may comprise a knob50/50″ and a threaded exterior surface 52/52″ that may complement athreaded interior channel 54/54″ of the first and/or second end 30A, 30Bthrough which the skull pin 24A/24A″, 24B/24B″ may pass. Rotation of theknob 50 by a user of the device 20 may advance or withdraw the skullpins 24A, 24B through the first and second ends 30A, 30B of the skullclamp 22. For example, a compressive direction of rotation applied tothe knob 50 of the first skull pin 24A may advance the plunger guide 46through the first end 30A to contract the compression spring 48, whichmay advance the plunger 44 and the first skull pin 24A toward the secondskull pin 24B. Thereby, with such advancement, the first skull pin 24Amay engage and apply an increasing compressive force against the head ofthe patient when the skull clamp 22 is positioned thereabout.Conversely, for example, a decompressive direction of rotation appliedto the knob 50 of the first skull pin 24A may draw the plunger guide 46through the first end 30A to extend the compression spring 48, which maydraw the plunger 44 and the first skull pin 24A away from the secondskull pin 24B. Thereby, with such withdrawal, the first skull pin 24Amay gradually reduce the compressive force applied against the head ofthe patient and, eventually, disengage the head. The skull pins24A/24A″, 24B/24B″ respectively may comprise an indicator 56/56″operable to indicate the compressive force applied by the respective tip42 against the head of a patient when the skull clamp 22 is positionedthereabout.

It is contemplated that, regardless of the respective configurations ofthe first and second skull pins 24A, 24B, the skull pins 24A, 24B arepositioned on the skull clamp 22 so that they are operable to applysubstantially equal compressive forces against the head of the patientwhen engaged therewith. Thereby, the head fixation device 20substantially fixates the head of a patient when engaged therewith and,when used in cooperation with the arc skull pin 57, minimizes thepotential for rotation of the head and for slippage of the skull pins24A, 24B along the head.

In addition to the first and second skull pins 24A, 24B provided to theskull clamp 22, the skull clamp arc assembly 26 comprises a skull pin57, referred to herein as the arc skull pin 57. As shown in FIG. 1A, theskull clamp arc assembly 26 extends from at least one of the first andsecond ends 30A, 30B of the skull clamp 22. Thereby, the arc skull pin57 is offset from the axis 40 and the first and second skull pins 24A,24B.

As shown in FIG. 3, the skull clamp 22 generally comprises a lockingassembly 58 provided at the first and/or second end 30A, 30B from whichthe skull clamp arc assembly 26 extends. The locking assembly 58 isoperable to secure the skull clamp arc assembly 26 to the first orsecond end 30A, 30B. The locking assembly 58 may comprise any variety ofone or more components and/or mechanisms to function as describedherein. In one embodiment, shown in FIG. 3, the locking assembly 58comprises a locking plate 60, an o-ring 62, and a snap ring 64. Thelocking plate 60 may be operable to secure immovably to the first orsecond end 30A, 30B of the skull clamp 22 and to support the skull clamparc assembly 26. The locking plate 60 may comprise at least one recess61 into which a locking pin 84 may insert to prevent movement of theskull clamp arc assembly 26 relative thereto, as described in greaterdetail below. The locking plate 60 also generally comprises a post 63and a depression 65 provided proximally to the end of the post 63. Theo-ring 62 is positionable about the post 63 and may be operable tofacilitate movement of the skull clamp arc assembly 26 relative to thelocking plate 60 and the first or second end 30A, 30B. The snap ring 64may be operable to secure the skull clamp arc assembly 26 to the lockingplate 60 by snapping or otherwise securing to the depression 65 in thepost 63 of the locking plate 60.

The skull clamp arc assembly 26 is movable relative to first or secondend 30A, 30B from which it extends such that the arc skull pin 57 isoperable to engage and disengage the head of a patient with movement ofthe skull clamp arc assembly 26. For example, in one embodiment, theskull clamp arc assembly 26 is rotatable relative to the first or secondend 30A, 30B such that the skull clamp arc assembly 26 rotates about theaxis 40.

In addition thereto, or in the alternative thereof, the skull clamp arcassembly 26 may be pivotable relative to the first or second end 30A,30B from which it extends such that the arc skull pin 57 may pivottoward and away from the axis 40. Thereby, the arc skull pin 57 mayengage and disengage the head of a patient when the skull clamp 22 ispositioned thereabout. For example, as shown in FIGS. 1B and 1C, theskull clamp arc assembly 26 may comprise a plurality of pivot points,whether two or more, pivot points 66A, 66B, such that the arc skull pinis pivotable relative to the first and second ends 30A, 30B and the axis40. Thus, by virtue of at least one of the rotational and pivotalmovements of the skull clamp arc assembly, the arc skull pin 57 may beselectively positioned as desired. Further, where the skull clamp arcassembly 26 is both rotatable and pivotable relative to the first orsecond end 30A, 30B from which it extends, as described above, tominimize potential for inadvertent rotational movement of the arc skullpin 57 along the head of a patient, the skull clamp arc assembly 26 maybe configured such that it is rotatable only with a pivoting of theskull clamp arc assembly 26 about at least one of the pivot points 66A,66B to a maximum pivot away from the axis 40.

The skull clamp arc assembly 26 may comprise one of any variety ofconfigurations comprising one or more of any variety of componentsand/or mechanisms suitable to enable the assembly 26 to function asdescribed herein. In one embodiment, shown in FIGS. 1B, 1C, and 3, theskull clamp arc assembly 26 comprises a rocker guide assembly 68, alower rocker assembly 70, and an upper rocker assembly 72. The rockerguide assembly 68 is securable to the one of the first and second ends30A, 30B from which the skull clamp arc assembly 26 extends. Further,the lower rocker assembly 70 is securable to the rocker guide assembly68 at the first pivot point 66A, while the upper rocker assembly 72 issecurable to the lower rocker assembly 70 at the second pivot point 66B.The lower rocker assembly 70 is pivotable about the first pivot point66A toward and away from the axis 40, while the upper rocker assembly 72is pivotable about the second pivot point 66B toward and away from theaxis 40.

As shown in FIG. 6, the lower rocker assembly 70 may comprise a lowerrocker arc 74, a cam 76, a pawl lever 77, and a recess 78 in the lowerrocker arc 74 at least partially housing the pawl lever 77. The lowerrocker assembly 70 may be locked and unlocked, via a ratchetconfiguration or otherwise, by a user of the head fixation device 20 topreclude and permit, respectively, pivoting of the lower rocker assembly70 about the first pivot point 66A. More particularly, the cam 76 maycomprise a grooved portion 79 that engages a ratchet 91 of the rockerguide assembly 68. The ratchet 91 may be spring-biased such that withdepression of a pawl 90 of the rocker guide assembly 68 by a user of thedevice 20, the ratchet 91 disengages the grooved portion 79 of the cam76, thereby enabling pivoting of the cam 76 and, thus, the lower rockerarc 74, relative to the rocker guide assembly 68. When the lower rockerarc 74 is positioned as desired, the user may release the pawl 90 of therocker guide assembly 68. The biasing spring thereby transitions theratchet 91 to engage the grooved portion 79 of the cam 76, locking it inplace.

The upper rocker assembly 72 may comprise an upper rocker arc 80 and acam 81, as shown in FIG. 7. The pawl lever 77 of the lower rockerassembly 70 may be actuated by the user to unlock the upper rocker arc80 of the upper rocker assembly 72 so that it is pivotable about thesecond pivot point 66B. Also, the pawl lever 77 may be actuated to lockthe upper rocker arc 80 so that the upper rocker assembly 72 is notpivotable about the second pivot point 66B. For example, the pawl lever77 may be spring-biased by a pawl lever spring 75 and comprise aprojection 77A operable to lock and unlock the upper rocker assembly 72so as to preclude and permit, respectively, movement thereof Thespring-biased pawl lever 77 may be depressed by a user to pivot theprojection 77A away from, and thereby disengage, the cam 81 of the upperrocker assembly 72 so that the upper rocker arc 80 may pivot toward andaway from the axis 40. Upon the user's release of the spring-biased pawllever 77, the lever 77 may transition to its relaxed state so that theprojection 77A pivots toward, and thereby engages, the cam 81 so thatthe upper rocker arc 80 assumes a locked state and is precluded frompivoting. The cam 81 may comprise a grooved portion 83 that may beengaged and disengaged by the projection 77A to prevent and enable,respectively, a ratcheted movement of the cam 81 and, thus, the upperrocker arc 80, relative to the lower rocker assembly 70.

Also, the upper rocker arc 80 may be operable to receive and support thearc skull pin 57 in the channel 85 extending at least partially throughthe arc 80. Thereby, the arc skull pin 57 may be operable to engage anddisengage the head of a patient with pivoting of the upper rocker arc 80about the second pivot point 66B toward and away from the axis 40.Further, as described herein with respect to the first and second skullpins 24A, 24B, the arc skull pin 57 may be movable independently of andrelative to the upper rocker arc 80 in which the arc skull pin 57 issupported so as to move toward and away from the axis 40. For example,the arc skull 57 may comprise a tip secured to the upper rocker 80 or,in addition to the tip, may comprise a plunger, a plunger guide, and acompression spring that may cooperate to move the tip relative to theupper rocker arc 80.

As shown in FIGS. 1B, 1C, 3, and 5, the rocker guide assembly 68 issecurable to the post 63 of the locking plate 60 provided to the one ofthe first and second ends 30A, 30B of the skull clamp 22 and may berotatable relative to the first or second end 30A, 30B such the skullclamp arc assembly 26 may rotate about the axis 40. Such rotation of theskull clamp arc assembly 26 may be restricted to a pivoting of at leastone of the lower rocker assembly 70 and the upper rocker assembly 72about the first pivot point 66A and the second pivot point 66B,respectively, to a respective maximum pivot away from the axis 40.

In one embodiment, the rocker guide assembly 68 may comprise a body 82,a locking pin 84, a recess 86 in the body 82 at least partially housingthe locking pin 84, a locking lever 88, a pawl 90, a ratchet 91, and achannel 92 through the body 82 through which the rocker guide assembly68 is securable to the post 63 of the locking plate 60. The rocker guideassembly 68 may be operable such that, as described above, withdepression of the pawl 90, a ratchet 91 releases from an engagement withthe cam 76 of the lower rocker assembly 70, thereby permitting it topivot about the first pivot point 66A. The user may pivot the lowerrocker assembly 70 until a desired position thereof is attained, atwhich time the user may release the pawl 90 from the depression, whichallows a spring 94 to bias the ratchet 91 to engage the cam 76 and lockit in position and to advance the pawl 90 to its projected state. As thelower rocker assembly 70 pivots to a maximum pivot away from the axis40, the cam 76 of the lower rocker assembly 70 engages the locking lever88 of the rocker guide assembly 68. With engagement thereof, the lockinglever 88 transitions the locking pin 84 from a locked state to anunlocked state so that the skull clamp arc assembly 26 is rotatablerelative to locking plate 60 and the first or second end 30A, 30B fromwhich it extends. As such, the skull clamp arc assembly 26 may rotateabout the axis 40.

More particularly, in one embodiment, the locking pin 84 is biased witha spring 98 to a locked state in which the locking pin 84 is insertedinto one of the recesses 61 in the locking plate 60, as shown in FIGS.1B, 1C, 3, and 5. It is contemplated that any number of recesses 61 maybe provided to the locking plate 60 to enhance the position-ability ofskull clamp arc assembly 26 relative to the skull clamp 22. Withmovement of the cam 76 to engage the locking lever 88, the locking lever88 contracts a biasing spring 98 and engages a recess 96 in the lockingpin 84. As the cam 76 continues to move, the locking lever 88, via itsengagement with the recess 96, retracts the locking pin 84 from therecess 61, thereby contracting the biasing spring 98 there-under.Retraction of the locking pin 84 unlocks the rocker guide assembly 68and permits rotation thereof relative to the locking plate 60 and aboutthe axis 40. An indicator 100 may be configured to project from the body62 of the lower rocker assembly 68 to indicate an unlocked status of therocker guide assembly 68 and its potential to rotate.

In addition, the rocker assembly guide 68 may be operable such that,with pivoting of the lower rocker assembly 70 about the first pivotpoint 66A other than to the maximum pivot away from the axis 40, the cam76 is disengaged from the locking lever 88. Thus, the spring 98 biasesthe locking pin 84 toward the locking plate 60 so that it inserts into arecess 61 in the locking plate 60. Thereby, the locking pin 84 maintainsa locked state so that the skull clamp arc assembly 26 is not rotatablerelative to the locking plate 60 and the first or second end 30A, 30Bfrom which the assembly 26 extends. More particularly, with movement ofthe cam 76 to disengage the locking lever 88, the biasing spring 98 isfree to expand to its relaxed state to transition the locking lever 88and the locking pin 84 from the retracted state into the recess 61 tothe locked state so as to prevent the rocker guide assembly 68 fromrotating.

Additional embodiments of the head fixation device are shown in FIGS. 2and 8. FIG. 2 illustrates a head fixation device 20′ comprising a skullclamp 22′, two skull pins 24A′, 24B′ movable relative to the skull clamp22′, and two skull clamp arc assemblies 26′, respectively comprising anarc skull pin 57′, that extend from the first and second ends 30A′, 30B′and are movable relative to the skull clamp 22′ and the axis 40′ alongwhich the two skull pins 24A′, 24B′ are aligned in opposition. Further,the skull clamp 22′ comprises a body 28′ having a more curvedconfiguration that is absent a ratcheting mechanism 36. Rather, thefirst and second skull pins 24A′, 24B′ respectively are operable to movelaterally and independently of the first and second ends 30A′, 30B′, asdescribed in greater detail below, so as to adjust the length of the gap32 separating the first and second skull pins 24A′, 24B′.

FIG. 8 illustrates another embodiment of a head fixation device 20″comprising a skull clamp 22″, two skull pins 24A″, 24B″ movable relativeto the skull clamp 22″, and two skull clamp arc assemblies 26″,respectively comprising an arc skull pin 57″, that extend from the firstand second ends 30A″, 30B″ and are movable relative to the skull clamp22″ and the axis 40″ along which the two skull pins 24A″, 24B″ arealigned. The skull clamp arc assemblies 26″ are illustrated asrespectively comprising only the first pivot point 66A″, rather thanboth the first and second pivot points 66A, 66B described herein. Inaddition, as shown in FIG. 10, the assembly 26″ may comprise a lockingpin 84″ operable to preclude and permit movement of the assembly 26″about the pivot point 66A″. Thus, while the disclosure provided hereingenerally is specific to one skull arc assembly 26 extending from one ofthe first and second ends 30A, 30B of the skull clamp 22, as shown inFIG. 1, it is contemplated that an embodiment of the head fixationdevice of the present disclosure, such as, but not limited to thoseshown in FIGS. 2 and 8, further may comprises a second skull arcassembly 26 that may be configured and operable in the same as thatdescribed herein or inferable there-from.

Further additional embodiments of the present disclosure relategenerally to methods of fixating heads of patients using embodiments ofthe head fixation devices of the present disclosure. For example, in oneembodiment, a method of fixating a head of a patient comprises providinga head fixation device operable to fixate the head of the patient. Thehead fixation device comprises: a skull clamp comprising a first end anda second end opposing the first end, a first skull pin provided to thefirst end of the skull clamp and a second skull pin provided to thesecond end of the skull clamp, wherein the first and second skull pinsare aligned in opposition along a axis, and a skull clamp arc assemblycomprising an arc skull pin, wherein the skull clamp arc assemblyextends from one of the first and second ends of the skull clamp suchthat the arc skull pin is offset from the axis and the first and secondskull pins aligned thereon. The head fixation device is then positionedabout the head of the patient such that the first and second ends of theskull clamp are positioned about the head of the patient. Thereafter, atleast one of the first and second skull pins are moved relative to thefirst and second ends of the skull clamp such that the first and secondskull pins engage the first and second sides of the head of the patientand the skull clamp arc assembly is rotated relative to the one of thefirst and second ends from which the skull clamp arc assembly extendssuch that the skull clamp arc assembly rotates about the axis toselectively position the arc skull pin over a third side of the head ofthe patient. Further, the skull clamp arc assembly is pivoted relativeto the one of the first and second ends from which the skull clamp arcassembly extends such that the arc skull pin pivots to engage the thirdside of the head of the patient. Engagements of the first, second, andthird sides of the head of the patient by the first skull pin, thesecond skull pin, and the arc skull pin, respectively, sufficientlyfixate the head of the patient.

It is contemplated that embodiments of the head fixation device of thepresent disclosure further may comprise one or more components operable,individually or in combination, to connect and/or secure the skull clampof the head fixation device to a surgical table or gurney. Suchcomponents may include, but are not limited to, table clamps, railclamps, and extension supports, that may attach, directly or indirectly,to the skull clamp.

Further, it is noted that recitations herein of a component of anembodiment being “configured” in a particular way or to embody aparticular property, or function in a particular manner, are structuralrecitations as opposed to recitations of intended use. Morespecifically, the references herein to the manner in which a componentis “configured” denotes an existing physical condition of the componentand, as such, is to be taken as a definite recitation of the structuralfactors of the component.

It is noted that terms like “generally,” “commonly,” and “typically,”when utilized herein, are not utilized to limit the scope of the claimedembodiments or to imply that certain features are critical, essential,or even important to the structure or function of the claimedembodiments. Rather, these terms are merely intended to identifyparticular aspects of an embodiment or to emphasize alternative oradditional features that may or may not be utilized in a particularembodiment.

For the purposes of describing and defining embodiments herein it isnoted that the terms “substantially,” “significantly,” and“approximately” are utilized herein to represent the inherent degree ofuncertainty that may be attributed to any quantitative comparison,value, measurement, or other representation. The terms “substantially,”“significantly,” and “approximately” are also utilized herein torepresent the degree by which a quantitative representation may varyfrom a stated reference without resulting in a change in the basicfunction of the subject matter at issue.

Having described embodiments of the present disclosure in detail, and byreference to specific embodiments thereof, it will be apparent thatmodifications and variations are possible without departing from thescope of the embodiments defined in the appended claims. Morespecifically, although some aspects of embodiments of the presentdisclosure are identified herein as preferred or particularlyadvantageous, it is contemplated that the embodiments of the presentdisclosure are not necessarily limited to these preferred aspects.

What is claimed is:
 1. A head fixation device comprising: a skull clamppositionable about a head of a patient, wherein the skull clampcomprises a first end and a second end opposing the first end; a firstskull pin provided to the first end of the skull clamp and a secondskull pin provided to the second end of the skull clamp, wherein thefirst and second skull pins are aligned in opposition along an axis, andwherein at least one of the first and second skull pins is movablerelative to the first and second ends such that the first and secondskull pins engage and disengage the head of the patient when the skullclamp is positioned thereabout; and a skull clamp arc assemblycomprising an arc skull pin, wherein the skull clamp arc assemblyextends from one of the first and second ends of the skull clamp suchthat the arc skull pin is offset from the axis, and wherein the skullclamp arc assembly is movable relative to the first and second ends ofthe skull clamp such that the arc skull pin is operable to engage anddisengage the head of the patient with movement of the skull clamp arcassembly.
 2. The head fixation device of claim 1, wherein: the one ofthe first and second ends of the skull clamp from which the skull clamparc assembly extends comprises a locking assembly operable to secure theskull clamp arc assembly to the one of the first and second ends, andthe locking assembly comprises a locking plate, an o-ring, and a snapring.
 3. The head fixation device of claim 2, wherein: the locking plateis operable to secure to the one of the first and second ends of theskull clamp from which the skull clamp arc assembly extends and tosupport the skull clamp arc assembly and comprises a post and adepression provided proximally to an end of the post, the o-ring ispositionable about the post of the locking plate and is operable tofacilitate movement of the skull clamp arc assembly relative to thelocking plate, and the snap ring is operable to secure to the depressionof the locking plate and secure the skull clamp arc assembly to the postof the locking plate.
 4. The head fixation device of claim 1, whereinthe skull clamp arc assembly is rotatable relative to the first andsecond ends such that the skull clamp arc assembly rotates about theaxis.
 5. The head fixation device of claim 1, wherein the skull clamparc assembly is pivotable relative to the first and second ends suchthat the arc skull pin pivots toward and away from the axis so as toengage and disengage the head of the patient when the skull clamp ispositioned thereabout.
 6. The head fixation device of claim 5, whereinthe skull clamp arc assembly includes a plurality of pivot points suchthat the arc skull pin is pivotable relative to the axis.
 7. The headfixation device of claim 6, wherein the skull clamp arc assembly isrotatable relative to the first and second ends such that the skullclamp arc assembly rotates about the axis with pivoting of the arc skullpin about at least one of the plurality of pivot points to a maximumpivot away from the axis.
 8. The head fixation device of claim 5,wherein the skull clamp arc assembly comprises: a rocker guide assemblysecurable to the one of the first and second ends from which the skullclamp arc assembly extends; a lower rocker assembly securable to therocker guide assembly at a first pivot point and pivotable about thefirst pivot point toward and away from the axis; and an upper rockerassembly securable to the lower rocker assembly at a second pivot pointand pivotable about the second pivot point toward and away from theaxis.
 9. The head fixation device of claim 8, wherein the rocker guideassembly is rotatable relative to the first and second ends such thatthe skull clamp arc assembly rotates about the axis with pivoting of atleast one of the lower rocker assembly and the upper rocker assemblyabout the first pivot point and the second pivot point, respectively, toa respective maximum pivot away from the axis.
 10. The head fixationdevice of claim 8, wherein the rocker guide assembly comprises a body, alocking pin, a recess in the body at least partially housing the lockingpin, a locking lever engaged with the locking pin, a cam movable toengage and disengage the locking lever, and a channel through the bodythrough which the rocker guide assembly is securable to the one of thefirst and second ends of the skull clamp.
 11. The head fixation deviceof claim 10, wherein: the rocker guide assembly is operable such thatpivoting of the lower rocker assembly about the first pivot point to themaximum pivot away from the axis moves the locking pin to an unlockedstate so that the skull clamp arc assembly is rotatable relative to thefirst and second ends such that the skull clamp arc assembly rotatesabout the axis, and the rocker guide assembly is operable such thatpivoting of the lower rocker assembly about the first pivot point otherthan to the maximum pivot maintains the locking pin in a locked state sothat the skull clamp arc assembly is not rotatable relative to the firstand second ends.
 12. The head fixation device of claim 8, wherein thelower rocker assembly comprises a lower rocker arc and pawl lever. 13.The head fixation device of claim 12, wherein: the lower rocker arc ispivotable about the first pivot point, and the pawl lever is movablebetween an unlocked state in which the upper rocker assembly ispivotable about the second pivot point and a locked state in which theupper rocker assembly is not pivotable about the second pivot point. 14.The head fixation device of claim 13, wherein the upper rocker assemblycomprises an upper rocker arc operable to receive and support the arcskull pin.
 15. The head fixation device of claim 14, wherein the arcskull pin is operable to engage and disengage the head of the patientwith pivoting of the upper rocker arc about the second pivot pointtoward and away from, respectively, the axis.
 16. The head fixationdevice of claim 15, wherein the arc skull pin is movable independentlyof and relative to the upper rocker arc in which the arc skull pin issupported.
 17. The head fixation device of claim 1, wherein the firstskull pin and the second skull pin respectively comprise a tip operableto engage and disengage the head of the patient when the skull clamp ispositioned thereabout, a plunger operable to support the tip, a plungerguide operable to control movement of the plunger and the tip, acompression spring operable to translate movement of the plunger guideto the plunger and the tip, and an indicator operable to indicate acompressive force provided by the tip against the head of the patientwhen the skull clamp is positioned thereabout.
 18. The head fixationdevice of claim 1, wherein the head fixation device comprises multipleskull clamp arc assemblies that extend from the first and second ends ofthe skull clamp.
 19. A head fixation device comprising: a skull clamppositionable about a head of a patient, wherein the skull clampcomprises a first end and a second end opposing the first end; a firstskull pin provided to the first end of the skull clamp and a secondskull pin provided to the second end of the skull clamp, wherein thefirst and second skull pins are aligned in opposition along an axis, andwherein at least one of the first and second skull pins is movablerelative to the first and second ends such that the first and secondskull pins engage and disengage the head of the patient when the skullclamp is positioned thereabout; and a skull clamp arc assemblycomprising an arc skull pin, wherein the skull clamp arc assemblyextends from one of the first and second ends of the skull clamp suchthat the arc skull pin is offset from the axis, wherein the skull clamparc assembly is rotatable relative to the first and second ends suchthat the skull clamp arc assembly rotates about the axis, and whereinthe skull clamp arc assembly is pivotable relative to the first andsecond ends such that the arc skull pin pivots toward and away from theaxis.
 20. A method of fixating a head of a patient, wherein the methodcomprises: providing a head fixation device operable to fixate the headof the patient, wherein the head fixation device comprises: a skullclamp comprising a first end and a second end opposing the first end, afirst skull pin provided to the first end of the skull clamp and asecond skull pin provided to the second end of the skull clamp, whereinthe first and second skull pins are aligned in opposition along an axis,and a skull clamp arc assembly comprising an arc skull pin, wherein theskull clamp arc assembly extends from one of the first and second endsof the skull clamp such that the arc skull pin is offset from the axis,positioning the head fixation device about the head of the patient suchthat the first and second ends of the skull clamp are positioned aboutthe head of the patient; moving at least one of the first and secondskull pins relative to the first and second ends of the skull clamp suchthat the first and second skull pins engage the first and second sidesof the head of the patient; rotating the skull clamp arc assemblyrelative to the first and second ends such that the skull clamp arcassembly rotates about the axis to selectively position the arc skullpin over a third side of the head of the patient; and pivoting the skullclamp arc assembly relative to the first and second ends such that thearc skull pin pivots to engage the third side of the head of thepatient, wherein engagements of the first, second, and third sides ofthe head of the patient by the first skull pin, the second skull pin,and the arc skull pin, respectively, sufficiently fixate the head of thepatient.